ABSTRACT In this paper, unvulcanized nitrile butadiene rubber (NBR)/polyvinyl chloride (PVC) mixtures were composed of Gamma 600 (72.6 wt%) as a filler to prepare NBR/ PVC/Gamma 600 composite. The samples were examined as a function of γ‐irradiation dose up to 300 kGy with different irradiation dose rates (0.5 and 1.0 kGy/h). The crystalline structure of all samples was examined using wide angle X‐ray diffraction. The swelling coefficients Q were calculated for the solvents (toluene, benzene, and chloroform), and inverse correlations between the diffusion coefficients and the irradiation doses for all the composites were observed. Calculations have been made to determine the conductivity and dielectric characteristics of the investigated composites. Improved charge carrier mobility was indicated by the frequency‐dependent behavior of the dielectric constant. Depending on the mixtures and irradiation dose, it was discovered that the conduction mechanism in the composite was investigated with correlated barrier hopping mechanism. Moreover, positron annihilation lifetime (PAL) spectroscopy showed that the free volume size shrinks with increasing γ‐irradiation for the samples irradiated with low or high irradiation dose rates. This shrinking is more pronounced for the 0.5 kGy/h γ‐irradiation dose rate samples. The crosslinking brought on by γ‐irradiation causes the free volume in the mixtures to diminish. Furthermore, there is a correlation between the macroscopic characteristics of the composites and the nanoscopic properties obtained via PAL spectroscopy.
Mohamed et al. (Thu,) studied this question.